Clamp.



H. L. SCOTT.

CLAMP.

APPLICATION FILED APR. 7. l9l7.

1 #382,643, I Patented Oct. 22, 1918.

I auueutoz Q/viX Meomw H 777 4 .8601 7 attouwt HENRY L. SCOTT, 0F PROVIDENCE, RHODE ISLAND.

CLAMP.

Specification of Letters Patent.

Patented Oct. 22, 1918.

Application filed April 7, 1917. Serial No. 160,583.

To all whom it may concern.

Be it known that I. HENRY L. SCOTT, a citizen of the United States, and resident of the city of Providence, in the county of Providence and State of Rhode Island, have invented certain new and useful Improvements in Clamps, of which the following is a specification.

This invention relates to clamps of th class employed to grip the work in testing machines in which the stretch and tensile strength of the material is measured. The object of the invention is to provide a clamp of the rolling jam type that may be employed in the testing-of any kind of ma terial, but the clamp herein shown is more particularly designed for use in testing round stock such as threads, fish lines, cords such as those used in tires, cat gut and other kindred materials, the clamp being so constructed that it will grip and hold the material without slipping and without mashing, cutting or otherwise weakening the sample being tested.

It is found in practice very' difficult to produce a clamp of this characterwhmh will engage the sample and hold the same without cutting or weakening the stock at the point where it is held, which weakening effect defeats the very object of a testlng machine designed to measure the actual breaking strength of the goods, to produce which result the goods must break at a point other than that where it is gripped.

A further object of the invention 1s to provide an eccentric member arranged to cooperate with a gripping face in the clamp to nip the work against it, the work is then led from the nipping point around the back and then around the front or offset portion of the roll to the next clamp. By this construction it will be seen that two advantages are obtained; first, an increased biting effeet on the goods as result of the increased leverage; and second, the work instead of leading directly now leads indirectly from the nip to the next clamp by which arrangement the work never breaks at the gripping point.

A further object of the invention is the arrangement whereby the connection is made to the clamp so that the pull on the clamp is substantially in line with the goods being tested.

With these and other objects in view, the invention consists of certain novel features of construction, as will be more fully described, and particularly pointed out in the appended claims.

In the accompanying drawings:

Figure 1 is a side elevation showing a pair of clamps gripping the piece of work extending between them, the rolls being partially sectioned to better show the nipping surfaces. r

2- is an edge elevation of one of the clamps showing the arrangement of the parts.

Fig. 3 is a sectional side elevation of the eccentric roll showing the spring acting thereon to cause it to automatically grip the goods against the block.

Referring to the drawings, 10 designates the frame portion of the clamp on which is mounted a block member 11 shown herein as being secured to the frame by means of thescrew 12 whereby it may swing to conform to the eccentricity of the capstan roll, but this block may be an integral portion of the frame if desired or connected thereto in any way, the essential feature being that the block provides a nipping face 13 against which the eccentric roll 14 bites. This roll is also mounted on the face to rotate on the screw 15, which screw is passed through a hole offset from the center of the roll thereby making the roll eccentric to the screw so that when rotated in one direction it bites against the nipping surface of the block, but in rotating in the opposite direction ,it opens a space between it and the block.

A handle 16 is provided for the operation of this roll.

The lower clamp as illustrated in Fig. 1 is provided with a boss 17 to which is secured the end of the tension screw 18, the axis of this screw being substantially in line in an u al with the surface of the offset portion of the roll when in engaging position, so that the tension will be exerted in line with the resistance through the goods a. This lower clamp is also shown as being provided with a boss 19 in which is mounted a hook 20 attached to a tape 21 which when drawn past the pointer 22 on the upper clamp indicates the stretch of the goods.

The upper clamp is shown as provided with a connector 23 whose axis is also substantially in line with the pull on the goods.

One of the essential features of this invention is that in positioning the goods to be tested in the clam 9 the roll is rotated by means of the operating handle 16 so as to provide a space between it and the gripping face of the block 11; the goods are then placed over the face of the block and carried around the back portion 24 of the roll then around the front or offset portion 25 of the roll and then around to the opposite-clamp to which it is attached in the same way, whereby when the tension is applied it will be seen that the pull on the goods rotates the roll in each clamp to bite the goods against its block, the pull of the goods acting on the front or offset portion of the roll providing a leverage to increase the'bite on the goods above the pull exerted, which increased grip absolutely prevents slipping at the bite. At the same time by passing the woods from the bite, around the roll, any weakness that may be caused by the excessive bite does not weaken the goods between their supporting or contacting points which is at the surface of the rolls, thereby causing the break to always occur at some point intermediate the clamps.

A flange 26 may be formed 011 the roll to facilitate positioning the work in the clamp and prevent its accidentally slipping over the end of the roll.

In some instances I find it of advantage particularly in the lower clamp of the pair to form the eccentri roll hollow as at 27, in Fig. 3, and mount a coiled spring 28 therein to act upon the roll so as to carry it automatically against the biting surface of the grip block.

I have illust 'ated one means whereby my invention may be carried out, but I do not wish to limit myself to the specific construction herein shown and described as various changes of the several features may be necessary. I, therefore, desire it .to be understood that I reserve the privilege of resorting to all the mechanical changes to which the device is susceptible, the invention being defined by the appended claims. I

I claim: a

1. A. clamp comprising a body portion having a gripping face, an eccentric capstan member cooperating with said face to nip the work against said face, the work being led from the nip point around the opposite side of said capstan and over its offset portion whereby the pull on the work causes said capstan to bite the work against said gripping face.

2. A clamp comprlsing a body member having a gri block mounted thereon, an eccentric capstan member also mounted on said body to engage said block to nip the work against it, said work being led from the nip point around the back and then around the offset portion of the capstan whereby tension on the work causes said capstan to nip the work against the block and a tension member connected to said body whose axis is substantially in line with the offset surface of said ro'll when positioned to nip the goods.

3. A clamp comprising a body member having a grip block mounted thereon, an cecentric apstan roll also mounted on said body to engage said block to nip the work against it, the work being led from the nip point around the back and then around the offset portion of the capstan whereby the pull of the Work upon the roll causes the work .to benipped against the block, said block being adjustable to accommodate the eccentric surface of said roll.

4. A clamp comprising a body member having a grip block mounted thereon, an eccentric capstan roll also mounted on said body to engage said block to nip the work against it, the work being led from theiiip point around the back and then around the offset portion of the capstan in leading to the next clamp, said capstan roll being supported from but one side to facilitate the positioning of the work thereover.

In testimony whereof I aflix my signature in presence of a witness.

HENRY L. SCOTT.

Witness HOWARD E. BARLOW.

Copies of this patent may be obtained ,for ,fiye cents each, by addressing the Commissioner of Patents,

' Washington, D. G. 

